This invention is related to industrial plate filters of the type used to filter liquids, such as the liquid coolants used during metal working operations, and more particularly to a low profile plate filter using only a single pair of filter plates.
During certain industrial processes large quantities of liquids must be filtered for reuse. One way to filter these liquids is with a stacked plate filter such as described in U.S. Pat. No. 3,608,734. Such filters direct the liquid through a number of filter plates stacked on top of one another and arranged for the parallel flow of liquid through them. With this arrangement, a central jack is used to seal the upper and lower surfaces of the filter plates. Although stacked plate filter apparatus is relatively expensive, because of the necessary multiple filter plates and associated filter paper rolls and filter paper extractor assemblies, they have proven to be reliable, efficient and are presently in wide use.
U.S. Pat. No. 2,867,236 to Hirs discloses filters of an older design which employ one or more pairs of stacked filter plates and various means for replacing contaminated filter media. It also discloses a gear drive mechanism for separating the filter plates or, alternatively, a pneumatic actuator mounted at the center of one of a pair of cooperating plates for raising and lowering the plate to permit the replacement of filter medium. By directly coupling the pneumatic actuator to one of the plates any pressure loss in the actuator, due to leaking seals, for example, can result in leakage of fluid from between the plates which, of course, is highly undesirable.